For the trade, wanted a dragon similar in concept to the sun. Like how the sun is there, giving warmth and life, but is also potentially destructive. This is what I came up with. My idea for it: the dragon got caught in a huge geological event, and is forever trapped and frozen, and over time, had mostly petrified, except for his chest, neck and head. In his attempt to escape the event, his wings were trapped in that position, forming a dome, and humans built a city in this area. Its protected by him, but does not receive much direct light. But a crystal has formed in the dragon's chest, reflecting the light and beaming it down into the dome.

Excellent! I love the way you captured the vague concepts I gave you in image form. The wings provide a barrier of protection around the city; however, the dragon could be very destructive to the city if it was still moving. The idea of having a crystal shine light down for warmth is also clever.